There was at that time a rather remarkable person in the… in the histology department called Alf Oettli, and Alf Oettli was a microscopist, and he believed in dark field microscopy, because he had learned this from a very famous man called Adrianus Pijper. Now, Adrianus Pijper was a man who had seen flagellae of bacteria under dark field, and of course it was through Alf Oettli that I really learnt about microscopy as a subject. One of the things that you needed to do this was an intense source of illumination, and so what we built was… is… was a heliostat. This was a mirror which effectively was hooked to a clock so that it followed the sun and would pick up the sun and reflect it into the lab so that we had with this heliostat and in the days of… of brilliant sunshine, especially that you get during the winter in South Africa, this report… this gave us a remarkable set of… gave us a remarkable source of illumination.